The present invention relates to a storage system and a data replication method, and more particularly to a storage system comprising plural storage control units to which plural disk devices are connected, and a data replication method for creation of replication.
Recently, demands for the reduction of time necessary for processing to create replication (hereinafter referred to as the backup) of data stored in a storage device of a storage system possessed by corporations in another storage device are increasing. Such demands are backed by the reduction of time allocated to the backup processing because an amount of information possessed by the corporations is increasing and the time for backup is increasing while business hours of corporations are extended.
The prior art enabling to backup data stored in a storage device without stopping the daily jobs of the corporations includes, for example, snapshot technologies proposed as described in JP-A-7-210439 and JP-A-2001-318833. The snapshot is a function to copy a storage area possessed by the storage device at a specified time to a storage device without through a computer connected to the storage device. Using such a snapshot function, a user can use the original storage area for jobs and the data stored in the copied storage area for backup.
As a technology for improving the scalability of the storage device connected to a network, a storage system of a cluster configuration is considered. The storage system of the cluster configuration is a system having a conventional storage system such as a disk array device as one cluster and one storage system configured of plural clusters.
Conventionally, no technology of performing snapshot in the storage system of a cluster configuration is known. Where the storage system of the cluster configuration and the snapshot technology of the above-described prior art are simply combined, copy of a storage area is performed only in one cluster.
As described above, where the storage system of the cluster configuration and the snapshot technology of the above-described prior art are combined, a storage area cannot be copied between different clusters, so that a storage area which can be used as a copy destination of a storage area and a storage area which cannot be used are formed within the storage system of one cluster configuration, causing a problem that the scalability of the storage system of the cluster configuration originally intended is impaired.
In the storage system of the cluster configuration, when it is made possible to copy a logical volume (hereinafter referred to as the volume) over clusters, namely when a copy source volume and a copy destination volume are on different clusters, a device configuration in that a cluster (hereinafter referred to as the original cluster) having a volume of the copy source cannot refer to a common memory within a cluster (hereinafter referred to as the copy cluster) having a volume of the copy destination or a device configuration in that reference can be made but access performance between the clusters is low has a problem that an efficiency of preparing a copy volume between different clusters is degraded. Therefore, the system configured as described above has a limited use that a volume of the copy destination is selected within the same cluster as the copy source. Thus, there is also a problem that the device configuration is different from the prior art and the ease-of-use by a user is changed.